Carburetor structure



poration or la St. .f Carbnretor Cotation, St. Lo,

Fdo., a cor- Application .lune E8, 1938, Serial No. 216,235

2 Gla. (Ul. 261e) This invention relates to carburetors for internal combustion engines and connsts icularly in novel accelerating and idling therefor.

A cir-mnding application, Serial No. 173,1d3 died November 6, 1937, in the name of the present inventor discloses and claims a carburetor having independent main nozzle and idling systems. the latter being provided with an air bleed controlled by a loaded check valve. This valve EJ tions prevail in the idling system whereby the is adapted to open when relatively high suctions prevail in the idling system so as to substantially lean out the iuel mixture supplied by the idling system, and to close when relatively low suc idling mii-:ture is enriched. The arrangement shown results in discharge from the carburetor ci 'a richer, more powerful fuel mixture at low suctions with the throttle partly open than is the Lcase where the main' nozzle and idling systems are interconnected, while at the same time providing for proper metering of fuel under normal idling and part throttle operation when the idling port is exposed to relatively high suctions and.

less fuel is needed. An 'automotive carburetor is preferably provided with an .accelerating device in addition to the main nozzle and idling systems.

In the present invention, an idling system, as

described in the above mentioned application is combined in a novel manner with the accelerating pump.

Accordingly, it is an object of the present invention to combine, in a simple construction. the

@d idling and accelerating systems in a carburetor.

A more detailed object is' to provide an accelerating system for a carburetor discharging adjacent the throttle valve and including an inlet check adapted to be opened by normal idling suctions in the system to provide idling fuel.

Another` detailed object is to provide an accelerating system for carburetors which discharges adjacent to and posterior to the throttle and otherwise arranged to function as an idling sysdi?) tem when the throttle valve is closed.

and sectioned, of a carburetor embodying a form of the invention.

Fig. 2 is an enlarged sectional view showing a detail of the structure of Fig. 1, and

Fig. 3 is a detail horizontal section taken substantially on the line 3 3 of Fig. 2.

Eig. d is a perspective view of the valve cage shown in section by Fig. 2.

The carburetor shown comprises a downdrait mixture conduit, including an air inlet hornl, venturls 2, t and d, mixing chamber 5, and out-- let portion e, ed as at l for attachment to the intake manifold (not shown) of an associ" ated internal combustion engine. Adjacent the `rifiniture conduit is a bowl t within which a sup- .ply of gasoline is maintained at a substantially constant level by needle valve mechanism t, controlled by a float lil. The needle valve controls the entry oi? fuel into the carburetor bowl from a remote supply. Fuel is supplied to the mixture conduit through a calibrated orice member ii,

frequently called the jet, and main nozzle l2 dis charging into the throat of the smallest venturi 2. Oriiice member il iscontrolled by a stepped metering rod i3, operated from throttle valve lil by means of an a l5, a link ia and a lever or rocker erm lb. i3 is yieldingly connected to the lever laas at il and is provided with an enlargement le adapted to seat against the upper surface of orifice member l l when the throttle valve is fully clos@ to prevent the paage of fuel from bowl. d into the main nozzle.

A cylinder l@ depends into another part of bowl 8 from cover portion zu thereof and slldably receives a piston 3i controlled from the throttle valve by means of an larm 22, which may be rimd with or a part of arm i5, a link 23, a pivoted lever 2d and rod 2b. Cylinder i9 communicates with the interior of bowl 8 through a passage 26 in the bottom wall thereof, this wall having an internal, annular ridge `El surrounding passage 2@ and forming a seat for disc check 28. Valve 28 also constitutes the` major part of the bottom wall of the pump cylinder. Cylinder l communlcates with the mixture conduit through passages 29, il@ and 3l and a port 32 inthe `wall of the mixture conduit adjacent and posterior to the edge of throttle valve l@ when the valve is closed. A calibrated restriction Si is provided in. e et. Passages i@ and 3l communicate with the mixture conduit anterior to venturis 2, t and t by means of air bleed holes te and 85. Air bleed 3d is controlled by a, check disc @t normally urged upwardly to close the air bleed by means of a coiled spring el, supported on a pin 3@ in passage di.

In operation, cylinder la and piston 2l comprise 'a pressure chamber and movable wallfor drawing fuel into the chamber and expelling the same therefrom and these, with passages 29, 36 and 3l, comprise an accelerating system for supplying a charge of accelerating fuel through port 32 when the throttle valve is opened. Closing of the throttle valve liitspiston 2|, drawing a supply of liquid fuel from the bowl or reservoir past inlet valve 28 into the pump pressure chamber in the lower part of cylinder I3. Piston 2|. 1s returned to its upper or charged position by a coiled spring 39 seated at the bottom against a I tion as an idling system for supplying a small.,

mixture to the mixture quantity of combustible conduit when the throttle valve is closed. 'The weight of disc check 23 is such as to permit lifting of this disc when relatively high` suction exists in passage 3| to permit vnormal functioning of the idling system and may be designed to close when less suction prevails in passage 3|, as when the throttle is opened suiiiciently to cause aspiration of fuel from the independent main nozzle. Bleed check 36 and spring 3l' are calibrated to open air bleed 34 into the idling system only under higher suction in passage 3| than is sufficient to open disc checlr 23, that is, when lower pressures exist in the idling system so -as to stop or decrease thedischarge of yfuel through passage 3| and port 32 at such time. This disc 36 functions, as explained in the abovementioned co-pending application, to lean out the idling discharge under normal idling and part throttle operation and to cut ofi' the air bleed when exposed to relatively low suction conditions to provide better power for part throttle operation. Disc checks 36 and 28 are both closed during discharge of the accelerating pump. Air

bleed 35 is positioned relative to passage 30 so that no gasoline will escape therethrough during discharge of the pump. Since the suction at port 32 will exceed that to which air bleeds 34 and.35 are exposed, whenever the throttle valve is partly closed, there will be a continual draft of air downwardly through passage 3| and port 32 to assist in carrying the accelerating charge into the mixture conduit and in vaporizing the same.

EnlargementV |8 on metering rod I3 cooperates with calibrated orifice member when the throt' tlel valve is closed to prevent flowing of liquid fuel from bowl 8 out through the main nozzle, such as frequently occurs after a hot engine is stopped due to boiling of the fuel in the restricted chamber at the base of the nozzle. this action benig known as percolation The arrangement shown attains the advantages nof an independent idling and main nozzle con- 'loss of function. I have shown the accelerating pump piston as actuated from the throttle valve, but this is not necessary4 and the piston may be otherwise actuated, if desired. The general features of the carburetor, as shown, are not essential and the arrangement of the various passages and other features may be varied as will occur to those skilled in the art. The exclusive use of all such modifications as come within the scope of the appended claims is contemplated.

I claim: l

1. In a carburetor, a mixture conduit having a throttle valve, a constant level fuel reservoir, an accelerating pump including a vertically arranged cylinder and a piston therein, a fuel inlet passage extending from the lower portion of said cylinder into said reservoir below the normal level therein, a combined idling fuel system and discharge nozzle for said accelerating pump comprising a passage extending from said cylinder to an idling port in the-wall of said mixture conduit on both sides of said throttle valve when closed, and an inlet check in' said inlet passage adapted to admit fuel when said piston is moved in the charging direction as well as when the carburetor is in operation with said throttle valve in idling position.

2. In a carburetor, a mixture conduit, a butteriiy throttle valve therein, there being idling port means located in the wall of said conduit so as to straddle the edge of said throttle when closed, a constant level fuel reservoir, an accelerating pump including a cylinder extending below the normal level in said reservoir and a piston, there b eing an inlet passage between said cylinder and said reservoir below the normal level therein, a discharge passage connecting said cyl inder adjacent said inlet passage and said idling port means, and an inlet check valve in said inlet passage constantly exposed to fluid pressure conditions in said cylinder whereby fuel will be discharged solely through said discharge passage and portl means upon actuation of said piston and whereby idling fuel may be drawn through said inlet passage, cylinder, and discharge passage.

IRVEN E. COFFEY. 

